The present invention is directed to a process of producing sulfonated polyester compounds suitable for use as a soil releasing agent and/or textile sizing agent in which a sulfonated acid or ester is reacted with a hydroxy-containing compound to form a sulfonated hydroxy terminated ester which then undergoes a transesterification reaction with a poly(ethylene) terephthate based polyester followed by polycondensation to form the desired sulfonated polyester compound. The present invention provides lower cost, reduced cycle times and improved yields over conventional processes for the production of sulfonated polyester compounds.
Sulfonated polyester compounds are known for removing soil and stains from a variety of substrates including filaments, fibers, fabrics, films and the like. Low molecular weight sulfonated polyester compounds are typically employed as soil release agents in laundry detergents while higher molecular weight sulfonated polyester compounds have been used for textile sizing.
U.S. Pat. No. 3,962,152 discloses a detergent composition containing polymers as soil release agents which are obtained by reacting dimethyl terephthalate with polyethylene glycol.
U.S. Pat. Nos. 4,863,619; 4,925,577 and 5,041,230 generally disclose methods of improving the processability of soil release polymers.
U.S. Pat. No. 4,999,128 discloses copolymers of poly(ethylene terephthalate/ethylene isophthalate) and related copolymers which are produced by reacting the esters with polyethylene glycol.
U.S. Pat. No. 5,142,020 discloses soil release promoters and detergents which are obtained by the polymerization of monomers such as dicarboxylic acid/ester/anhydride, dihydric alcohols and polyethylene glycols.
Sulfonated polyester compounds have received increased attention as effective soil release agents. For example, U.S. Pat. No. 3,557,039 discloses a stable aqueous dispersion comprising water and a water insoluble crystallizable block or graph polymeric compound which contains linear polyethylene terephthalate segments having sufficient ethylene terephthalate units to confer crystallinity to the compound. These polymers are prepared by reacting monomers which include dimethyl sodium sulfoisophthalate.
U.S. Pat. No. 4,427,557 discloses sulfonated copolymers used for preparing anionic textile treating compositions in which the polymerizable monomers include dimethyl sulfoisophthalate.
U.S. Pat. No. 4,702,857 discloses sulfonated copolymers used as soil release agents in detergent formulations in which the copolymers are obtained by polymerizing monomers such as dimethyl terephthalate, dimethyl sulfoisophthalate, polyethylene glycol and polyethylene glycol monoether.
U.S. Pat. No. 5,599,782 also discloses sulfonated polyester compounds useful as soil release agents. Polymerizable monomers which are mentioned in the reference include m-sodiosulfobenzoic acid, dimethylsodiosulfoisophthalate, dimethyl terephthalate, terephthalic acid and ethylene glycol.
U.S. Pat. No. 5,728,671 discloses sulfonated polyester compounds useful as soil release agents having whitening properties.
U.S. Pat. No. 5,786,318 discloses polymerizing such monomers as sulfonated aromatic dicarboxylic acids to produce soil release polymers for detergent compositions. Other soil release polymers containing sulfonated polymers are disclosed in U.S. Pat. Nos. 5,789,365; 5,789,366; and 5,789,367.
The market for polyester compounds for use as soil releasing agents and/or textile sizing agents and particularly sulfonated polyester compounds for this purpose has increased significantly in recent years. However, increased demand has spurred efforts to improve production capability of the desired sulfonated polyester compounds.
Traditional methods of producing sulfonated polyester compounds for use as soil releasing agents and/or textile sizing agents are problematical for reasons which include expensive starting materials, lengthy process cycle (i.e. the time it takes from the initial reaction to the production of a finished product) and low yields of the desired product or relative low reactor throughput. By way of example, the production of a sulfonated polyester compound through a transesterification reaction of dimethyl terephthalic and dimethyl-5-sulfoisophthalate with excess ethylene glycol, followed by esterification with terephthalate acid and then polycondensation undergoes a typical cycle time of about 38.5 hours for processing a 15 ton batch of polyester. Since the reaction produces 35% of distillate, the long cycle time and low yield or reactor throughput makes it very difficult to meet the requirements of the growing market demand for such sulfonated polyester compounds.
The present invention is directed to a process for the production of sulfonated polyester compounds in which reaction yields and cycle time are significantly improved over conventional processes for the production of the same or similar compounds. The present method is generally directed to the production of a sulfonated polyester compound suitable for use as a soil releasing agent and/or textile sizing agent in which a sulfonated acid or corresponding alkyl ester is reacted with a hydroxy-containing compound to produce a sulfonated ester intermediate compound which is then reacted with a polyester compound selected to afford the final polyester compound with a desired molecular weight.
In a particular aspect of the present invention, there is provided a method of producing a sulfonated polyester compound suitable for use as a soil releasing agent and/or textile sizing agent comprising:
a) reacting at least one compound of Formula (I)
XSO3xe2x80x94Rxe2x80x94(COOY)nxe2x80x83xe2x80x83(I)
wherein
X is a cation,
R is an aryl group,
Y is selected from the group consisting of hydrogen and an alkyl group, and
n is a positive integer with at least one compound of Formula (II)
R1xe2x80x94(OH)mxe2x80x83xe2x80x83(II)
wherein R1 is selected from the group consisting of an alkyl group, a cycloalkyl group and an aryl group, which may be substituted with an alkyl group or an aryl group, and m is a positive integer and optionally with a compound of Formula (III)
R2xe2x80x94(COOZ)pxe2x80x83xe2x80x83(III)
wherein R2 is selected from the group consisting of an alkyl group and an aryl group, Z is selected from the group consisting of hydrogen and an alkyl group, and p is a positive integer, and optionally with a compound of Formula (IV) 
wherein R3 and R4 are each independently selected from the group consisting of hydrogen and an alkyl group, and q is a positive integer to produce at least one ester compound intermediate, and reacting the resulting ester compound intermediate with a homoxe2x80x94or co-poly(ethylene terephthalate) to produce the sulfonated polyester.
The method of producing a sulfonated polyester compound in accordance with the present invention for use as a soil releasing agent and/or textile sizing agent begins with the reaction of at least one compound of Formula (I)
xe2x80x83XSO3xe2x80x94Rxe2x80x94(COOY)nxe2x80x83xe2x80x83(I)
wherein X is a cation, R is an aryl group which may be substituted with an alkyl group or an aryl group, Y is selected from the group consisting of hydrogen and an alkyl group and n is a positive integer. The cations available for X include, for example, sodium, lithium, potassium, NH4 and tetrabutylphosphonium. Sodium is the preferred cation for the compound of Formula (I). R is an aryl group and includes, for example, phenyl, and naphthyl.
The starting sulfonated compound may be in the form of an acid wherein Y is hydrogen or in the form of an alkyl ester. Preferred alkyl groups are methyl, ethyl, propyl and butyl with methyl being the preferred alkyl group. The number of acid or ester groups is from 1 to 4, preferably 1 or 2. The most preferred number of acid or ester groups is 2.
Examples of suitable compounds of Formula (I) include dimethyl-5-sodiosulfoterephthalate, 5-sodiosulfoterephthalic acid, 5-lithoisophthalic acid, 3-sodiosulfobenzoic acid, and 4-sodiosulfodiphenyl-4, 4xe2x80x2-dicarboxylic acid. The preferred compounds of Formula (I) are sodiosulfoisophthalic acid and 3-sodiosulfobenzoic acid.
The compound of Formula (I) is reacted with a hydroxy-containing compound of Formula (II) R1xe2x80x94(OH)m. The hydroxy-containing compound can be selected from monols, diols and polyols. R1 is selected from the group consisting of unsubstituted alkyl, cycloalkyl, and aryl groups which may be substituted with an alkyl group and an aryl group. Preferred alkyl groups are those having 1-8 carbon atoms most preferably methyl, ethyl, propyl, and butyl. Preferred cycloalkyl groups are those having 5 to 8 carbon atoms such as cyclohexanyl. Preferred aryl groups for R1 include phenyl and naphthyl. M is preferably in the range of from 1 to 4, most preferably 2. Preferred compounds of Formula (II) include ethylene glycol, 1,2- propylene glycol, 1,3-propanediol, neopentyl glycol, glycerol, 1,2 butylene glycol, 1,4-butanediol, 2,2-dimethyl-1,3-propanediol, 1,6-hexanediol and 1,4-cyclohexanedimethanol.
In addition to compounds of Formulas (I) and (II), the reaction can also be also conducted in the presence of a compound of Formula (III).
R2xe2x80x94(COOZ)pxe2x80x83xe2x80x83(III)
depending on the application of the final polymer. R2 is selected from the group consisting of an alkyl group and an aryl group, which may be substituted with an alkyl group or an aryl group. Z is selected from the group consisting of hydrogen and an alkyl group and p is a positive integer. Preferred alkyl groups are those having 1-12 carbon atoms. Preferred alkyl groups for Z are those having 1-4 carbon atoms. Preferred values for P are 1 and 2. Exemplary compounds where R2 is an alkyl group include adipic, succinic, sebacic, azelaic, glutaric and suberic acids and their corresponding alkyl esters. Exemplary compounds where R2 is an aryl group include terephthalic, isophthalic, orthophthalic, 1,2-naphthalene dicarboxylic, 1,4-naphthalenedicarboxylic, 1,5-naphthalenedicarboxylic, 1,6-naphthalenedicarboxylic, 1,7-naphthalenedecarboxylic, 1,8-naphthalenedicarboxylic, 2,3-naphthalenedicarboxylic, 2,6-naphthalenedicarboxylic, 2,7-naphthalenedicarboxylic acids and their corresponding alkyl esters.
A compound of Formula (IV) may also be used as an optional starting material 
wherein R3 and R4 are each independently selected from the group consisting of hydrogen and an alkyl group and q is a positive integer.
Preferred alkyl groups for R3 are those having 1-4 carbon atoms. Preferred alkyl groups for R4 are those having 1-12 carbon atoms especially methyl and lauryl. Preferred values for q are 2-20. Exemplary compounds of the optional material of Formula (IV) include polyethylene glycol, polypropylene glycol and block copolymers of polyethylene glycol and polypropylene glycol and their corresponding alkyl monoethers. The compounds of Formula (IV) preferably have a molecular weight of no more than about 1,000.
The reaction of the compounds of Formulas (I) and (II) optionally in the presence of at least one compound of Formulas (III) and (IV) is typically conducted at a temperature of from about 120 to 280xc2x0 C., preferably from about 130 to 190xc2x0 C. The reaction is typically carried out in the presence of a catalyst capable of catalyzing esterfication and/or transesterification reactions, such as, for example titanium (IV) (triethanolaminato) isopropoxide, titanium (IV) propoxide, titanium (IV) butoxide, manganese acetate, antimony trioxide, hydrated monobutyltin oxide and magnesium oxide. Other suitable catalysts would be well known to these skilled in the art. The preferred catalyst is titanium (IV) (triethanolaminato) isopropoxide.
The reaction of the compounds of Formulas (I) and (II) and optionally at least one compound of Formulas (III) and (IV) produces at least one ester compound intermediate. The ester compound intermediate is then reacted continuously or intermittently with a homoxe2x80x94or co-poly(ethylene terephthalate) to produce the desired sulfonated polyester compound. This reaction is typically conducted at a temperature of from about 150 to 280xc2x0 C., preferably form about 180 to 260xc2x0 C. Depending on the desired molecular weight, a vacuum of from about 600 to 0.5 mmHg can be applied after all of the poly(ethylene terephthalate) has melted.
The preferred poly(ethylene terephthalate) compounds for reacting with the ester compound intermediate is a copolymer of polyethylene terephthalate and comonomers selected from the group consisting of isophthalate, diethylene glycol, propylene glycol, and 1,4-cyclohexanedimethanol. The resulting reaction produces a sulfonated polyester compound wherein the position and number of sulfonated groups are determined by the suitable selection of the starting materials. By selecting a compound of Formula (I) wherein n is 1, at least some of the sulfonated groups will appear as an end group in the polyester chain. By employing at least one compound of Formula (I) wherein n is greater than 1, at least some of the sulfonated groups will appear intermittently in the polyester compound and not as an end group.
The following examples are illustrative of the embodiments of the invention and are not intended to limit the invention as encompassed by the claims forming part of the application.